To get an idea of how people think about Hydraulic Drives check out this request on another Forum:

"I'll rephrase my question. I want to us a 25 hp Honda air-cooled engine, in a VW. How big of a motor will it take to drive 65 mph, how big of a oil pump will it take supply the hydraulic motor or motors? I have invented a hydraulic piston mud pump for the drilling industry and believe we can make a car go 70 mph using hydraulic oil."

I find this is somewhat typical of how the lack of training leads to MAGICAL HAPPENINGS when it comes to the world of HYDRAULICS.

To drive a vehicle you need to determine and know the following figures:
Gross weight,weight on driving wheels,diameter of drivining wheels,number of driving wheels ,top speed at maximum torque,ground rolling resistance,gradeability,frontal area,acceleration,draw bar pull,prime mover speed,maximum pressure and more. Vehicle Drive
by hydrostatics is a long path of calculations.

Sounds like they were reading a Mother Earth News article from 1975!

ISZ

Factoring all the coefficients would be a breeze. I'm not sure a 25hp VW could hit 65mph with mechanical drive, however.

Did someone tell him he'd be lucky to get 18hp at the axles? And how is it someone has the engineering capacity to invent a piston pump, but can't figure out things like tractive effort or torque?

Take a look at this article in the Machinery Lubrication magazine on Hydraulic drive efficiency to get an idea of why hydraulic vehicle drives are not looming on the horizon.

Also why I don't believe Wind Powered Generators will jump to Hdraulic drives.

http://www.machinerylubrication.com/article_detail.asp?...intenance+Department